This read-write object controls whether the receive spectrum is treated as normal(0) or inverted(1). Spectrum inversion happens when a satellite transponder or LNB inverts the signal's frequency spectrum during frequency translation, so this setting must match the actual polarity of the incoming signal -- if left at normal(0) when the actual spectrum is inverted, the demodulator will fail to correctly interpret the modulated data even while showing RF lock. When switching to a transponder known to produce an inverted spectrum, common with certain LNB/downconverter combinations, an admin would set this to inverted(1) to correctly recover the data.